Artists such as singers, film producers or videographers may record and make available more than one version of a particular composition, or multiple variations of a part of a composition. Such versions may include for example an acoustic version of a song, an electric or synthesized version of the same song, a hip-hop version, a classical version, etc. Similarly, various artists may record and make available their own cover versions of the same song. Other artists may wish to create a composition that may include certain variations of parts of the original composition, or of parts of variations of similar or different compositions.